Jane Fonda has revealed she has been diagnosed with cancer.

In an Instagram post Friday, the "Grace and Frankie" star and two-time Oscar winner, 84, announced she has begun chemotherapy treatment for non-Hodgkin’s lymphoma.

According to Mayo Clinic, non-Hodgkin’s lymphoma is a cancer of the lymphatic system in which white blood cells cause tumors throughout the body.

Treatment can involve chemotherapy, radiation therapy, targeted drug therapy, immune cell engineering, a bone marrow transplant and immunotherapy.

"This is a very treatable cancer," Fonda wrote. "I feel very lucky."Fonda also expressed gratitude for her health insurance and having "access to the best doctors and treatments" — something she knows many people with cancer don't have.

"I realize, and it’s painful, that I am privileged in this," she wrote. "Almost every family in America has had to deal with cancer at one time or another and far too many don’t have access to the quality health care I am receiving and this is not right."

Fonda, who has in recent years built a reputation as a climate change activist, also said more needs to be done to address the root causes of cancer, particularly pesticides.

Other causes of non-Hodgkin’s lymphoma, according to Mayo Clinic, include medications that suppress the immune system, certain viral and bacterial infections and old age.

The actress said her chemotherapy will last six months and that she's handling the treatment "quite well."